Assigning two shortcuts for the same action
There is a way, but it's a very bad idea
You should not do it. Middle click is used too much to practically change it and retain important functionality in Blender's keymaps.
You would have to add a new entry here in the Preferences(F4 -&gt; P), Keymap tab, under Screen, Screen(Global):

But you would also have to search for and remove all the conflicts:

That would break stuff.
This would be a very bad idea.